A new Tomlinson-Harashima precoding scheme based on RVQ feedback with fewer bits

Tomlinson-Harashima precoding exceeds traditional linear precoding system with higher sum rate and lower bit error rate in high signal-to-noise ratio region. In this paper, a novel THP scheme based on limited feedback for Multi-user MIMO system is studied. Based on limited feedback bits, our proposed optimized THP scheme with a modified receiver, which needs feedback channel direction information only, gets the same performance as original system with perfect channel amplitude information (CMI) feedback, and about 3-4dB gains are obtained compared with no CMI feedback situation. Our analysis and the validity of the optimization algorithm are verified by simulation results. Without CMI feedback, the proposed scheme has cut down feedback overheads significantly in THP precoding system which is essential for its implementation for the next generation system. At the same time, the conclusion that channel vector quantization excels to unitary precoding codebook in THP scheme has also been drawn in this paper.